The present invention relates to an apparatus for identifying tires and a method thereof. More particularly, it relates to an apparatus for identifying tires wherein it is identified whether the tires are summer tires or winter tires for the purpose of improving performance and safety of a vehicle equipped with a limited slip differential device (LSD).
Since longitudinal grooves and vertical grooves are engraved in tires for drainage purposes, rubber blocks are formed surrounded by these grooves. A block of large size is hardly deformed through shear strength in vertical and lateral directions and presents high rigidity. Such a tire having a tread pattern which comprises such a large block is called a tire of large pattern rigidity.
Since cornering power, cornering force as well as slip rate are largely affected by the degree of the pattern rigidity, it is required to know the pattern rigidity of the tires in order to estimate behaviors of a vehicle based on rotational information of the tires in case the vehicle is equipped with a means for improving the performance and safety of the vehicle by utilizing rotational information of tires such as ABS (anti-lock braking system), TCS (traction control system) or NAVI (navigation system). Generally, the pattern rigidity of a summer tire is large and that of a winter tire small.
It is also conventionally known that a decrease in tire air-pressure results in a smaller dynamic load radius of the tires so that the rotational speed becomes faster than that of tires of normal air pressure. Japanese Unexamined Patent Publication No. 149119/1995 discloses one example of a method for detecting decrease in internal pressure based on relative differences in the number of revolutions of tires. Further, since the rotational speed of tires is affected by many factors such as turning movement, acceleration or deceleration, load or speed of the vehicle, it has been variously devised to eliminate influences of these.
However, among vehicles that are manufactured in these years, there are some that are equipped with a limited slip differential device at differential gears of driving shaft for the purpose of improving running performances at the time of cornering or the like. Due to the mechanism of such a limited slip differential device, differentiation is restricted until a differential torque exceeds a set value, and right and left driving wheels are rotated at equal speeds. Due to this arrangement, influences of decreases in air pressure are not reflected in the number of revolutions so that a decompressed condition cannot be detected based on relative comparison of the number of revolutions.
While tuning of an apparatus for alarming decrease in tire air pressure that is controlled based on rotational information of tires is performed as to be suitable to tires attached to a new car, it was conventionally the case that estimations of behaviors of the vehicle were largely different from initially tuned values in case the tires were changed from summer tires to winter tires or, vice versa, from winter tires to summer tires, since these largely differ from each other in their specifications. Consequently, there existed the danger that incorrect information could be transmitted to the driver.
The present invention has been made in view of these circumstances, and it is an object thereof to provide an apparatus for identifying tires and a method thereof with which is it possible to identify whether the tires are summer tires or winter tires in a vehicle equipped with a limited slip differential device.
In accordance with the present invention, there is provided an apparatus for identifying between summer tires and winter tires based on rotational information that can be obtained from tires attached to a four-wheeled vehicle equipped with a limited slip differential device, wherein the apparatus comprises a rotational information detecting means for detecting rotational information of each of the tires, a memory means for storing rotational information of each of the tires, an arithmetic processing means for respectively calculating reciprocals of turning radiuses based on rotational information of tires attached to a driving shaft from among rotational information of each of the tires as well as judged values based on rotational information of each of the tires, and an identification means for identifying whether the tires attached to the driving shaft are summer tires or winter tires from a relationship between reciprocals of turning radiuses and the judged values.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
In accordance with the present invention, there is also provided a method for identifying between summer tires and winter tires based on rotational information that can be obtained from tires attached to a four-wheeled vehicle equipped with a limited slip differential device, wherein it is identified whether tires attached to the driving shaft are summer tires or winter tires from a relationship between reciprocals of turning radiuses as calculated from rotational information of tires attached to the driving shaft of the four-wheeled vehicle and judged values as calculated from rotational information of tires attached to the four-wheeled vehicle.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: